1Taken from list archive at http://lists.arm.linux.org.uk/pipermail/linux-arm-kernel/2001-July/004064.html23Initial definitions
4-------------------
56The following symbol definitions rely on you knowing the translation that
7__virt_to_phys() does for your machine. This macro converts the passed
8virtual address to a physical address. Normally, it is simply:
910 phys = virt - PAGE_OFFSET + PHYS_OFFSET
111213Decompressor Symbols
14--------------------
1516ZTEXTADDR
17 Start address of decompressor. There's no point in talking about
18 virtual or physical addresses here, since the MMU will be off at
19 the time when you call the decompressor code. You normally call
20 the kernel at this address to start it booting. This doesn't have
21 to be located in RAM, it can be in flash or other read-only or
22 read-write addressable medium.
2324ZBSSADDR
25 Start address of zero-initialised work area for the decompressor.
26 This must be pointing at RAM. The decompressor will zero initialise
27 this for you. Again, the MMU will be off.
2829ZRELADDR
30 This is the address where the decompressed kernel will be written,
31 and eventually executed. The following constraint must be valid:
3233 __virt_to_phys(TEXTADDR) == ZRELADDR
3435 The initial part of the kernel is carefully coded to be position
36 independent.
3738INITRD_PHYS
39 Physical address to place the initial RAM disk. Only relevant if
40 you are using the bootpImage stuff (which only works on the old
41 struct param_struct).
4243INITRD_VIRT
44 Virtual address of the initial RAM disk. The following constraint
45 must be valid:
4647 __virt_to_phys(INITRD_VIRT) == INITRD_PHYS
4849PARAMS_PHYS
50 Physical address of the struct param_struct or tag list, giving the
51 kernel various parameters about its execution environment.
525354Kernel Symbols
55--------------
5657PHYS_OFFSET
58 Physical start address of the first bank of RAM.
5960PAGE_OFFSET
61 Virtual start address of the first bank of RAM. During the kernel
62 boot phase, virtual address PAGE_OFFSET will be mapped to physical
63 address PHYS_OFFSET, along with any other mappings you supply.
64 This should be the same value as TASK_SIZE.
6566TASK_SIZE
67 The maximum size of a user process in bytes. Since user space
68 always starts at zero, this is the maximum address that a user
69 process can access+1. The user space stack grows down from this
70 address.
7172 Any virtual address below TASK_SIZE is deemed to be user process
73 area, and therefore managed dynamically on a process by process
74 basis by the kernel. I'll call this the user segment.
7576 Anything above TASK_SIZE is common to all processes. I'll call
77 this the kernel segment.
7879 (In other words, you can't put IO mappings below TASK_SIZE, and
80 hence PAGE_OFFSET).
8182TEXTADDR
83 Virtual start address of kernel, normally PAGE_OFFSET + 0x8000.
84 This is where the kernel image ends up. With the latest kernels,
85 it must be located at 32768 bytes into a 128MB region. Previous
86 kernels placed a restriction of 256MB here.
8788DATAADDR
89 Virtual address for the kernel data segment. Must not be defined
90 when using the decompressor.
9192VMALLOC_START
93VMALLOC_END
94 Virtual addresses bounding the vmalloc() area. There must not be
95 any static mappings in this area; vmalloc will overwrite them.
96 The addresses must also be in the kernel segment (see above).
97 Normally, the vmalloc() area starts VMALLOC_OFFSET bytes above the
98 last virtual RAM address (found using variable high_memory).
99100VMALLOC_OFFSET
101 Offset normally incorporated into VMALLOC_START to provide a hole
102 between virtual RAM and the vmalloc area. We do this to allow
103 out of bounds memory accesses (eg, something writing off the end
104 of the mapped memory map) to be caught. Normally set to 8MB.
105106Architecture Specific Macros
107----------------------------
108109BOOT_MEM(pram,pio,vio)
110 `pram' specifies the physical start address of RAM. Must always
111 be present, and should be the same as PHYS_OFFSET.
112113 `pio' is the physical address of an 8MB region containing IO for
114 use with the debugging macros in arch/arm/kernel/debug-armv.S.
115116 `vio' is the virtual address of the 8MB debugging region.
117118 It is expected that the debugging region will be re-initialised
119 by the architecture specific code later in the code (via the
120 MAPIO function).
121122BOOT_PARAMS
123 Same as, and see PARAMS_PHYS.
124125FIXUP(func)
126 Machine specific fixups, run before memory subsystems have been
127 initialised.
128129MAPIO(func)
130 Machine specific function to map IO areas (including the debug
131 region above).
132133INITIRQ(func)
134 Machine specific function to initialise interrupts.